Flexible guide clamp safety system



April 29, 1969 B, G, THORNE ET AL 3,441,107

FLEXIBLE GUIDE CLAMP SAFETY SYSTEM Filed June 26, 196'? Sheet of 2 FIG. l INVENTORS BENJAMIN GRAHAM THORNE H LD JAMES NS A RT VINCEN 01 FE April 29, 1969 THQRNE ET AL 3,441,107 A FLEXIBLE GUIDE CLAMP SAFETY SYSTEM Sheet 3 of2 Filed June 26, 196'? INVENTORS BENJAMIN GRAHAM THORNE HAROLD JAMES LYONS- ALBERT VINCENT DINGFELD .BYMXWTQRNEY FlG.2

United States Patent 3,441,107 FLEXIBLE GUIDE CLAMP SAFETY SYSTEM Benjamin Graham Thorne, Yonkers, Harold James Lyons,

Greenlawn, and Albert Vincent Dingfeld, Brooklyn,

N.Y., assignors to Otis Elevator Company, New York,

N.Y., a corporation of New Jersey Filed June 26, 1967, Ser. No. 648,827 Int. Cl. B66b 5/16; B25g 3/38; F16c 11/06 US. Cl. 187-90 7 Claims ABSTRACT OF THE DISCLOSURE A flexible guide clamp safety system for elevator cars in which rail engaging members are raised by lift rods fastened near the center thereof into position to be urged by guide blocks into engagement with the guide rail.

FIELD OF THE INVENTION This invention relates generally to elevator systems and particularly to safety systems for elevator cars in which excessive speed of the car causes rail gripping members carried by the car to be urged into engagement with the guide rails so as to decelerate and stop the car.

BACKGROUND Flexible guide clamp safety systems have been known and widely used for many years. A typical system comprises a pair of mounting assemblies fastened to the car beneath the platform, one adjacent to each of the guide rails. Each assembly includes a pair of guide blocks, one on each side of the rail but spaced substantially therefrom, each block being formed so that the surface facing the rail is inclinedto the vertical being closer to the rail at the top than at the bottom. These guide blocks are slideable horizontally toward and away from the rail in grooves or slots formed in the mounting assembly and both are urged by a strong spring toward the rail and into engagement with stops which hold them a substantial distance away from the rail. The mounting assembly also includes a pair of rail engaging members or shoes each horizontally positioned between the guide block and the rail and vertically positioned a little lower than the guide block. That face of each rail engaging member adjacent to the rail is parallel thereto and is normally spaced slightly therefrom. The opposite face is inclined in a direction parallel to the face of its associated guide block. Between each rail engaging member and its guide block are several rollers held in a cage or frame. The rail engaging members are each held in their normal, inactive positions by a generally vertically extending lift rod bolted to one side thereof near the top. Each lift rod is operatively connected to a speed responsive device such as a governor which, in response to downward overspeed of the car, raises the lift rods relative to the car. The lift rods raise the shoes and as the latter are raised, they are urged, by virtue of the inclined surfaces and the rollers, into engagement with the rail with a pressure determined by the strength of the previously mentioned spring. Upward movement of the rail engaging shoes is terminated when they strike a stop member fastened to the mounting assembly directly above the shoes but to one side of the lift rods, which rods extend upward beside the stop member. The retarding force of the shoes against the rail is transferred to the stop member, the mounting assembly and the car.

A safety system such as briefly described above is more fully described in the Hymens Patent No. 2,150,373. Such systems have been entirely satisfactory with elevators operating up to 600 or 800 feet per minute. However, when used with higher speed elevators, difficulties arise. These difficulties are first manifested by a bending or breaking of the bolts fastening the lift rods to the rail engaging shoes. The reason for the difficulties can best be understood after considering the operation of a typical governor.

A governor, as usually used in an elevator system, comprises a sheave rotatably mounted in the machine room. One end of a rope is fastened to the lift rod operating mechanism on the car and from there extends up and over the sheave, down to the pit, around a tensioning sheave and back up to the lift rod mechanism. The latter mechanism is made stiff enough, as by a detent arrangement, so that it normally remains unoperated and the car simply drives the rope and the sheaves at speeds corresponding to car speed. The sheave in the machine room is operatively connected to a speed responsive device, such as a pair of fly balls or weights pivoted to the sheave, which, in response to downward overspeed of the car, release a pair of jaws which grip the governor rope between them. Such gripping slows the downward movement of the rope and lift rods and overcomes the detent arrange ment thereby raising the lift rods relative to the car.

Examining the operation more closely, as the car is descending at less than the critical speed, the governor rope, the governor sheave and the tensioning sheave are all in motion. When the governor trips, the jaws grasp the rope decelerating the entire mass. The rope slows to a speed less than that of the car and may even stop altogether. The rail gripping shoes rise (relative to the car) until they strike or are struck by the stop member fastened to the mounting means. The shoes, the lift rods and the governor rope must now be accelerated rapidly to car speed. Additionally, the rope must be pulled through the jaws of the governor and must accelerate the governor sheave and the tensioning sheave. The necessary forces are transmitted from the stop member to the rail engaging shoes and through the bolts to the lift rods and the governor rope. It will be recalled that each lift rod is bolted to one side of the shoe so that there is an off center force which tends to rotate the shoe out of engagement with the stop member. It has been found that the bolt tends to bend and/or break much more readily than might otherwise be expected. The only way that the problem has been met hitherto, as far as applicants are aware, has been by increasing the size and strength of the various parts. However, such techniques have their limits.

It is a general object of the present invention to provide an improved flexible guide clamp safety system.

Another object is to provide a flexible guide clamp safety system better able to withstand the forces generated during acceleration of the governor rope and its associated masses.

Another object is to provide a flexible guide clamp safety system better able to withstand the forces arising when the rail engaging members strike or are struck by the stop member on top of the mounting assembly.

SUMMARY Briefly stated, a preferred embodiment of the invention comprises a rail engaging member or shoe arranged to engage the rail to one side of it and the stop member above it in much the usual manner when drawn upward by a lift rod. However the lift rod, instead of being bolted to one side of the shoe, is fastened at approximately the center thereof. Various fastening arrangements can be used but in the embodiment preferred at present, the lift rod extends through a substantially vertical aperture near the middle of the shoe and is fastened by a barrel nut extending through a horizontal aperture intersecting the vertical aperture. The barrel nut has a cylindrical upper surface complementary to that of the horizontal aperture so as to engage a large area of the shoe. At the same time, the

barrel nut permits a small amount of rotation of the lift rod, sufficient to accommodate the lateral movement of the shoe as it rises. Additionally, the lift rod passes freely through an aperture in the stop member, instead of to one side. As a result, the off center forces are substantially eliminated, thereby greatly strengthening the mechanism.

For a clearer understanding of the invention reference may be made to the following detailed description and the accompanying drawing, in which:

FIGURE 1 is a schematic elevation view of an elevator system incorporating the invention;

FIGURE 2 is an elevation view, partly in section, of one of the safety assemblies;

FIGURE 3 is a view, partly in plan and partly in section, taken on the line 33 of FIGURE 2;

FIGURE 4 is an enlarged elevation view, partly in section, of a detail showing a preferred arrangement for fastening a lift rod to a rail engaging member;

FIGURE 5 is a plan view of a detail showing an alternative arrangement for fastening a lift rod to a rail engaging member; and

FIGURE 6 is a cross section view taken on the plane 6-6 of FIGURE 5.

Referring first to FIGURE 1, there is shown schematically an elevator car 11 equipped with four guide assemblies 12 which cooperate with a pair of rails 13 and 14 which extend vertically on opposite sides of the hoistway. The car 11 is supported by hoist ropes 15 fastened thereto which extend upward into the machine room over a traction sheave 16 and downward to a counterweight (not shown). Fastened to the same shaft as the sheave 16 is an electric motor 17 and an electromagnetic brake 18.

The car 11 is also provided with a pair of safety assemblies 21 and 22, one on each side of the car beneath its platform and adjacent to the rails 13 and 1 4 respectively. These assemblies are normally inactive and come into play only upon overspeed of the car whereupon they grip the rails 13 and 14 and stop the car, as will be more fully explained. The assembly 21 is operated by a pair of lift rods, only one of which, the rod 23, is shown in FIGURE 1, the other being directly behind it. Similarly, the assembly 22 is operated by a lift rod 24 and another one behind it. The rods 23 and 24 are connected to bell crank levers 25 and 26 respectively which are interconnected by a link 27 so as to operate in unison. These levers are fastened to pins 28 and 29, respectively, carried by a frame member 31 extending across the top of the car. On the far side of the frame member 31 the pins 28 and 29 are fastened to additional bell crank levers which also are interconnected to act in unison and which are connected-to the remaining lift rods. By this arrangement, all four lift rods are constrained to move in unison.

The bell crank lever 25 is connected to a governor rope 32 which extends upward into the machine room and around a sheave 33 of a governor 34, then down to the pit and around a tensioning sheave 35 and back to the lever 25. In normal operation, all of the lift rods are held in the positions shown by a spring biased detent arrangment 36 and as the car 11 moves, the rope 32 and the sheave 33 are driven at a speed corresponding to the speed of the car.

The governor 34 may be any of several kinds, it only being necessary that it grip the rope 32 as a predetermined speed is reached. One satisfactory kind is shown schematically and includes a stationary rope gripping jaw 37 mounted adjacent to one side of the rope 32 and a swinging jaw 38 adjacent to the other side of the ripe and held above and out of engagement therewith by a latch mechanism 39. The sheave 33 is equipped with a pair of weights 41 and 42 pivotally mounted thereon which fly outward in response to centrifugal force as the speed of the sheave 33 increases and, at a predetermined speed, trip the latch mechanism 39 thereby releasing the jaw 38 which falls by gravity into engagement with the rope 32 opposite the jaw 38. When this happens, the rope 32 and the right arm of the bell crank lever 25 are decelerated, the detent 36 is overcome and the lift rods descend more slowly than the car. This slower descent is more conveniently thought of as at raising of the lift rods with respect to the car and causes the safeties to grip the rails, as will be more fully explained.

Referring now to FIGURES 2 and 3, each safety assembly 21 and 22 comprises a mounting block 45, which may be a casting and which includes an upper portion 46 which serves as a stop member and a lower portion 47. A pair of guide blocks 48 and 49 are each formed with upper and lower projecting portions (not shown) which make sliding fits with grooves (not shown) in the upper and lower portions 46 and 47 so that the guide blocks may move horizontally. The inner surface of the guide blocks 48 and 49, that is, those surfaces facing the rail 13, are faced with hardened wear strips 51 and 52 respectively and are inclined to the vertical as shown with the upper portion closer to the rail than the lower portion. The outer face of each guide block 48, 49 is substantially vertical except that each is made with a recess in the form of a segment of concave spherical surface. A spring, which may, for example, be a horizontally disposed U-shaped spring 55, is equipped with a pair of pins having heads 56 and 57 in the form of convex spherical segments which engage the recesses in the guide blocks 48 and 49 and urge them inwardly toward each other and toward the rail 13. Such inward movement is limited by the engagement of shoulders formed at the top and bottom of each of the guide blocks with abutments rigidly fastened to the upper and lower portions of the guide block 45. Typical of the four cooperating shoulders and abutments is the shoulder 61 formed at the top of the guide block 48 and the abutment 62 in the form of a key positioned in a groove in the upper portion 46 of the mounting block 45 and bolted thereto.

A pair of rail engaging members, or shoes, 64 and 65, are positioned on opposite sides of but not touching the rail 13, one adjacent to each of the two side guiding surfaces 66 and 67 of the rail 13. The surface of the rail engaging member 64 which faces the rail 13 is substantially planar and parallel to the vertical side guiding surface 66, while the opposite surface is faced with a hardened wear strip 68 and is inclined to the vertical and substantially parallel to the inclined surface of the adjacent guide block 48. The rail engaging members 64 and 65 normally occupy the positions shown with the top thereof considerably below the top of the adjacent guide blocks 48 and 49. The lift rods 23 and 23 extend through oversized apertures or slots 71 and 72 in the upper portion or stop members 46 and are fastened to the rail engaging members 64 and 65 as will be more fully explained.

Between each of the rail engaging members or shoes 64 and 65 and their associated guide blocks 48 and 49 are a plurality of rollers 74. The group of rollers between the shoe 64 and the guide block 48 are typical and these are mounted for rotation about horizontal axes on a frame comprising a pair of shallow, facing channel members 75 and 76, separated by spacers 77 and 78. The channel members 75 and 76 slidingly embrace the edges of the wear strips 51 and 68, which, as best shown in FIGURE 3, are wider than the guide block 48 and the shoe 64 so as'to constitute guideways for up and down movement of the channels 75, 76 with respect to the shoe 64 and the guide block 48. A spring 81 acting between a bracket 82 fastened to the portion 47 of the guide block 45 and the spacer 7'8 urges the rollers 74 and their frame 75, 76 downward to the position shown to which position they are limited by the engagement of one of the rollers 74 with an upstanding end 83 of the bracket 82.

The rail engaging member 64 is typical and, as best shown in FIGURE 4, is formed with a horizontal bore 84 near the top extending completely therethrough in a direction parallel to the side guiding surface 66 of the rarl 13 and approximately midway between the vertrcal and inclined faces. The member 64 is also formed with a vertical bore 85 extending from the center of the horizontal bore 84 upward through the upper surface at approximately the center thereof. The upper portion of the bore 85 is slightly enlarged relative to the lower portion. The lift rod 23 extends through the vertical bore 85 into the horizontal bore 84 where it threadedly engages a self locking barrel nut 86. The nut 86 is an elongated nut having a cross section in the shape of a segment of a crrcle and formed with a threaded radial aperture. As shown, the convex surface of the nut, which preferably extends for slightly more than one hundred and eighty degrees, complements and engages the upper concave surface of the horizontal bore 84 thereby affording a large area of contact between the nut 86 and the member 64.

In operation, the parts occupy the positions shown in the drawing during normal operation of the car 11. As the car moves downward, the governor rope 32 moves along with it, rotating the governor sheave 33 and the tension sheave 35. Upon downward overspeed of the car 11, the jaws 37, 38 grip the rope 32 decelerating it rapidly, perhaps even stopping it completely. The force thus generated overcomes the detent arrangement 36 and slows the descent of all four lift rods. Regarding the car 11 as a reference point for a moment, the lift rods are raised, raising the rail engaging members 64, 65. As they rise, the action of the inclined surfaces urges them inwardly into engagement with the side guiding surfaces 66 and 67 of the rail 13. Upon further upward movement the members 64, 65 roll on the rollers 74 which also roll on the inclined surfaces of the guide blocks 48, 49 forcing them outward against the urging of the spring 55. The members 64, 65 grip the rail 13 between them with a force determined by the strength of the spring 55. Finally, the tops of the members 64, 65 engage the bottom load bearing surface of the stop portion 46. The retarding force of the friction between the stationary rail 13 and the moving rail engaging members 64, 65 is transferred to the portion 46 and to the car 11, thereby decelerating it.

As the rail engaging members 64, 65 engage the stop portion 46, the downward movement of the car 11 suddenly accelerates these members to car speed. Large forces are generated because all four lift rods, the governor rope 32, the governor sheave 33 and the tensioning sheave 35 must also be accelerated and in addition the rope 32 must be pulled through the jaws 37, 38. These forces must be transmitted from the rail engaging members to the lift rods. It is to be noted that, in the present arrangement, each lift rod 23, 23' extends approximately through the center of the top surface of its associated rail engaging shoe 64 and 65 and that the center line of the lift rod, produced, passes approximately through the center of the shoe. As a result, forces are transmitted from the shoe to the lift rod without the generation of the off center forces or moments characteristic of some prior arrangements. Additionally, it is to be noted that the forces are transmitted from the large concave surface of the horizontal bore to the corresponding surface of the barrel nut from which they are transmitted through the threads to the lift rod, all without lost motion and without eccentricities.

It is also to be noted that as the rail engaging shoe 64 is raised from its normal, lowermost position, it moves laterally into engagement with the rail 13. To follow this motion, the lift rod must also move laterally and must rotate slightly with respect to the shoe 64. The enlarged vertical bore 85 in the shoe 64 and the slot 71 in the stop member 46 accommodate the lateral movement while the barrel nut 86 rotates readily within the shoe 64.

Referring now to FIGURES 5 and 6 there is shown another arrangement for fastening the lift rod to the rail engaging member. In this embodiment, the rail engaging member or shoe 91 is formed with a wide slot 92 on the top extending from one side to a point beyond the center leaving a U-shaped upstanding portion. The end of the lift rod 94 is in the form of an eye bolt which is positioned within the slot 92 and fastened to the legs of the U with a bolt 96 and a nut 97. It is apparent that this form of fastening is similar in many respects to that previously described in that the center line of the lift rod 94 extended, passes approximately through the center of the member 91, in that the pull is direct without eccentricities, and in that the lift rod may rotate slightly with respect to the member 91. This arrangement may be preferred in some cases although for most applications the previously described arrangement including the barrel nut is preferred at present.

The invention has been described as applied to an elevator car but it is apparent that it could also be used with a counterweight.

Although the invention has been described in considerable detail for illustrative purposes, modifications will occur to those skilled in the art so we do not desire that the invention be limited to the particular arrangement which has been described.

What is claimed is:

1. A safety system for an elevator car movable in a hatchway, and guided by a longitudinally extending rail, comprising, first and second rail engaging members on opposite sides of said rail adjacent thereto but normally disengaged therefrom, guide means mounted on said car adjacent to said members for resiliently urging them into engagement with said rail upon upward movement of said members relative to said car and guide means, first and second generally vertically extending lift rods mounted on said car and fastened to said first and second members respectively, first and second stop means mounted on said car and respectively disposed adjacent said first and second lift rods for respectively limiting upward movement of said first and second members relative to said car, and means responsive to a predetermined downward speed of said car for lifting said rods relatively to said car, whereby said members are urged into engagement with said rail and with said respective stop means, each of said lift rods being fastened to its associated rail engaging member in a position such that the extension of the center line of said rod passes through said member, and each of said stop means having at least a pair of stop portions, said pair of stop portions being disposed in the path of travel of its associated rail engaging member and being disposed on radially opposite sides of its associated lift rod.

2. A safety system in accordance with claim 1 in which each lift rod is positioned relative to its associated rail engaging member so that the extended center line of said rod passes approximately through the middle of said member, and in which each said pair of stop portions is a pair of adjacent portions of a substantially horizontal plate, each said pair of plate portions forming therebetween a substantially vertical aperture through which its associated lift rod passes freely.

3. A safety system in accordance with claim 2 in which each of said lift rods is so fastened to its associated rail engaging member as to have a limited amount of freedom of rotation about an axis which is substantially horizontal and parallel to the side guiding surfaces of said rail, and in which said pairs of stop portions have respective load bearing surfaces facing their associated rail engaging members, said load bearing surfaces being disposed in a common plane which is substantially horizontal and at right angles to the side guiding surfaces of said rail.

4. A safety system in accordance with claim 3 in which each of said rail engaging members is formed with a first generally horizontally extending cylindrical bore near the top thereof and with a second generally vertical bore extending from said first bore upward through the top of said member approximately at the center thereof, and in which the lower end of each of said lift rods extends through said second bore in its associated rail engaging member, and also including a member positioned in said first bore engaging the upper surface thereof and fixedly connected to said end of said lift rod, and in which said vertical bores and said vertical apertures have respective axes, said axes being substantially disposed in a common plane, said plane substantially including the center lines of said lift rods.

5. A safety system in accordance with claim 4 in which the lower end of each of said lift rods is formed with external threads and in which said member positioned in said first bore is an elongate pivot member having a curved upper surface complementary to and in engagement with the upper surface of said first bore and said pivot member is formed with an aperture disposed approximately midway between the ends thereof having internal threads which engage said external threads on said rod.

6. A safety system in accordance with claim 3 in which said load bearing surfaces have respective areas which contact said rail engaging members, said contact areas having a common axis of symmetry, said axis being dis- 8 posed in a substantially vertical plane, said plane substantially including the center lines of said lift rods.

7. A safety system in accordance with claim 6 in which said rail engaging members have respective rail engaging surfaces, said rail engaging surfaces having respective axes of symmetry, said axes of symmetry being substantially disposed in said vertical plane including the axis of symmetry of said contact areas of said stop portions.

References Cited UNITED STATES PATENTS 2,150,373 3/1939 Hymans 187-90 2,297,649 9/ 1942 Donaldson 287-2l 2,547,124 4/ 1951 Hudson 287-21 2,719,608 10/1955 Callaway 187-90 3,346,074 10/1967 Borden 187--88 EVON C. BLUNK, Primary Examiner. H. C. HORNSBY, Assistant Examiner.

U.S. C]. X.R. 2872l 

